Fix all remaining weird Diffusion request processing
Summary: Ref T4245. This is the last of it, and covers the clone/push stuff.
Test Plan:
- Cloned git.
- Pushed git.
- Cloned mercurial.
- Pushed mercurial.
- Visited a blah.git URL in my browser just because; got redirected to a human-facing UI.
Reviewers: chad
Reviewed By: chad
Maniphest Tasks: T4245
Differential Revision: https://secure.phabricator.com/D14949